This project is identifying important elements of protein structure by network analysis. We model the protein structure by amino acid or hydrogen-bond networks, where the interaction between the individual elements are obtained from the more detailed X-Ray and NMR structure of the protein. The project is aimed to predict and experimentally verify important amino acids or amino acid groups which play an important role in the biological function of the studied protein. Our target proteins include those of the cytochrome P450 family as key members of drug metabolism.